Balloon



FIG. 1 is a front perspective view of a balloon showing my new design;

FIG. 2 is a rear perspective view thereof;

FIG. 3 is a front elevational view thereof shown on a reduced scale; and

FIG. 4 is a side elevational view thereof, the side opposite being a mirror image.

The broken line showing of ropes and a gondola in FIGS. 1 through 4 is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a balloon, as shown and described. 